How do I finish an Activity from within a Presenter or a View in the mortar sample app?
The majority of the time you would want to avoid doing this. But in dire circumstances you could follow the same pattern the ActionBarOwner[0] class implements. Create an injectable class that exposes Activity#finish via an interface.
Item 3 in [1] is related but the calling order is inverted. (Activity lifecycle methods to presenters instead of Presenters to Activity methods).
Hope that helps!
[1] Mortar + Flow with third party libraries hooked to activity lifecycle